1. Field of the Invention
The present invention relates to a wireless communication device.
2. Description of the Related Art
In recent years, with the remarkable spread of data communication that is performed in a wireless manner, there have been advances in high communication speed, miniaturization of a wireless communication device, and low power consumption. For example, wireless communication in compliance with a Digital Enhanced Cordless Telecommunications (DECT) scheme that has been spread worldwide as a communication scheme for digital cordless telephones is stipulated in ETSI EN 300 175-2: “Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI); Part 2: Physical Layer (PHL),” ETSI EN 300 175-3: “Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI); Part 3: Medium Access Control (MAC) layer,” and ETSI EN 300 175-5: “Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI); Part 5: Network (NWK) layer.” Also in Japan, the use of wireless devices in compliance with the DECT scheme was approved, and wireless communication devices, such as a cordless telephone and an intercommunication system, have been of practical use. Time division multiplex communication is employed in the wireless communication in compliance with the DECT scheme. A base unit that operates as a control station transmits a control signal that serves as a reference for timing for the time division multiplex communication. A handset that operates as a slave station establishes synchronization for the time division multiplex communication by receiving a control signal, and performs communication. While changing a reception frequency for every frame, the base unit waits for a connection request from the handset, and notifies the handset of information relating to a change in a standby frequency, using a control signal. In a case where communication between the base unit and the handset is started, the handset tunes the standby frequency of the base unit, determines a frequency, and notifies the base unit of a communication starting request. The base unit receives the communication starting request, and thus the communication between the base unit and the handset is started.
In recent years, a system in which household electrical appliances within a house are controlled from outside of the house, a household crime prevention system, or the like has gained popularity. Developments in wireless communication for communication between apparatuses on such a home automation network have been made. A method for packet communication suitable for communication between apparatuses on the home automation network, which is based on the wireless communication in compliance with the DECT scheme, is stipulated in ETSI TS 102 939-1: “Digital Enhanced Cordless Telecommunications (DECT); Ultra Low Energy (ULE); Machine to Machine Communications; Part 1; Home Automation Network (Phase 1)” (communication that is stipulated in ETSI TS 102 939-1: “Digital Enhanced Cordless Telecommunications (DECT); Ultra Low Energy (ULE); Machine to Machine Communications; Part 1; Home Automation Network (Phase 1)” is hereinafter referred to as DECT ULE communication). An object of the DECT ULE communication is to apply the DECT ULE communication to a battery-operated wireless communication device such as a sensor device that has the same usage value as a window sensor in the crime prevention system. Furthermore, a technology is disclosed that is useful for an improvement in responsiveness and for realization of low power consumption. For example, a method is disclosed in which in the ULE communication, the base unit detects a level of an interfering wave and notifies the handset of a threshold of detection of the interfering wave in a reception environment in the base unit and information (hereinafter expressed as channel information) on an empty slot that is determined with the threshold. In a case where the communication is started between the base unit and the handset, the handset operates in such a manner that the slot that is notified with the channel information that is sent from the base unit is selected and the communication is activated. Accordingly, the frequency with which a communication path fails to be activated due to interference caused by the interfering wave is reduced, and the improvement in responsiveness and the reduction in power consumption are realized.